1. Field of the Invention
The present invention relates to a highly specific anti-Caveolin-1 polyclonal antibody, an antigen and a method used for preparing said antibody, and a kit used for detecting Caveolin-1 in a specimen.
2. Description of the Related Art
Caveolin-1 is a 21-24 kDa membrane protein containing 178 amino acid residues, and it is abundant in caveolaes. Caveolaes are invaginations of the plasma membrane, and cholesterol and signal transducing molecules are accumulated in these invaginations. Both N- and C-terminal domains of Caveolin-1 are hydrophilic and oriented toward the cytoplasm, while the hydrophobic central stretch is embedded in the membrane. The N-terminal region of Caveolin-1 (amino acid residues 82-101) is necessary for its interaction with signal transducing molecules, while the C-terminal region (amino acid residues 135-178) is essential for Caveolin-1 dimer formation from its monomers, and for the membrane attachment of Caveolin-1. Caveolin-1 expression in mammals is down-regulated during late pregnancy and lactation through a prolactin signaling cascade. Overexpression of recombinant Caveolin-1 in mammary epithelial cell line HC11 inhibits the β-casein expression induced by prolactin. In addition, mammary gland development in Caveolin-1 null mice is earlier than in normal mice (Park et al., 2001). Therefore, Caveolin-1 acts as a negative regulator during mammary development and lactation. If Caveolin-1 expression in medium and large lactating animals can be detected, it may be helpful to study the role played by Caveolin-1 in the mammary gland.
In pathology studies, it has been found that Caveolin-1 expression is lost or down-regulated in many tumorous tissues of, for example, breast, ovary, prostate and colon cancers, and Caveolin-1 is regarded as an indicator for the progression of these cancers (Sloan et al., 2004; Wikman et al., 2004). Another prior study has found, using mRNA subtractive hybridization, that there is an obvious difference between Caveolin-1 gene expression in normal and tumorous human mammary epithelial cells (Sager et al., 1994). Another study found that Caveolin-1 expression in mammary adenocarcinoma-derived cells was much lower than in normal mammary epithelial cells. When Caveolin-1 was overexpressed in tumor cell lines, cell tumorigenesis was suppressed (Park et al., 2001). Ectopic expression of recombinant Caveolin-1 in mammary adenocarcinoma cells through cell transfection reduced the metastatic potential of these cells (Zhang et al., 2000). These studies have demonstrated that Caveolin-1 is anti-tumorigenic and can be used as a molecular indicator to diagnose the progression of some cancers.
The current method of detection of Caveolin-1 protein in tissues and cells is by immunochemical or immunofluorescent staining, and there are dozens of commercial anti-Caveolin-1 antibodies in the market. However, most of these commercial anti-Caveolin-1 antibodies are produced by the antigen derived from N-terminal amino acid residues 1-20 or 30-44 of Caveolin-1, and some of them are produced by the antigen derived from C-terminal of Caveolin-1. Bush et al. (2006) used five different anti-Caveolin-1 antibodies (developed by other teams) to detect the location of expressed Caveolin-1 in MDCK cells, and found that the specific locations of Caveolin-1 detected by different antibodies were different. This finding indicates that different anti-Caveolin-1 antibodies vary in their ability to label Caveolin-1 in cells, and the Caveolin-1 signals detected by these antibodies show different patterns.
Therefore, an anti-Caveolin-1 antibody with a higher efficiency to Caveolin-1 will be extremely advantageous for cancer research and the development of cancer treatments.